Osmium (element)
鋨 is a rare kanji for the chemical element osmium. Its meaning is limited to that specific element.
鋨 is a modern character created for the element osmium. It combines the metal radical 金 with the phonetic component 我, which likely provides the sound テツ.
The metal radical 金 on the left marks it as a metallic element. The right side 我 (oneself) can remind you that osmium is a dense, self-contained metal.
For テツ, imagine a piece of osmium metal that is as hard as iron (鉄, てつ). The shared reading テツ links the rare element to a familiar metal.